Corrugated binder strap



CORRUGATED BINDER STRAP Filed Sept. 19, 1962 d W it/md. Smmdm MA ills I 6 BY ja/m2sN.W03nunn hfilei w pnaflu 4d?) United States Patent 3,235,071 CORRUGATED BINDER STRAP Emil Simich and llamas N. Wognum, Chicago, Ill., assignors to lnterlake Steel Corporation, a corporation of New York Filed Sept. 119, 1962, Ser. No. 225,174 4 Claims. (Cl. 206-835) This invention relates to improvements in binder straps of a type used for binding packages, boxes, freight bracing, or the like.

With the ordinary type of metal strapping presently extensively used, it has a tensile strength in a range of up to about 130,000 p.s.i. and is of sufficient relative softness, although actually hard, to permit strap tensioning tools to be employed for tensioning the strap around the object to be bound. The strap is soft enough to allow suflicient penetration of the sharp teeth of tensioning grippers embodied in these tools for effectuating the tensioning by movement of these grippers without slippage on the strap. Presently, however, there is a trend toward use of metal strapping having higher tensile strength, in the range of up to about 200,000 p.s.i. Techniques have been developed whereby ordinary low carbon steel can be heat treated to this tensile strength. When so treated, it has been found that this high tensile metal strapping is much harder than the strapping having the lower tensile strength. In fact, it is so hard that the gripping members of conventional strapping tools both wear out more quickly because of failure to penetrate sufficiently and slippage of the grippers over this high tensile strapping and fail to grip the strapping sufficiently to permit tensioning to the magnitude of tensioning required. There exists a serious problem because there has been a substantial demand for the use of the higher tensile strength strapping.

It is the principal object of this invention to provide an improved high tensile metal strapping which permits tools having conventional strap grippers to be used efliciently. The manner of accomplishing this is to impart a corrugated transverse cross-section to the strapping. The corrugated shape divides the strap into small areas of contact from which create greater force concentrations at the small areas of contact with the strap grippers used and this causes the gripper teeth to grasp the strap more firmly and minimize slippage.

The cor-rugating of the strapping in this manner also provides other unobvious advantages. It provides an overall improved appearance to the strapping resulting, at least in part, by camouflaging ordinary finish imperfec tions. The corrugating also imparts a limited amount of rigidity to the strapping which permits even narrow and thin and otherwise highly flexible strapping to be wound into ribbon wound coils. The corrugations nest with each other and provide a stability to the ribbon wound coil which permits it to be self-supporting when wound. Previously, the lighter gauge strap was necessarily wound in an oscillated manner where the strand is oscillated from one side to the other of the coil as it is wound. Another advantage of the corrugated strapping due to its rigidity is that, when fed around a strap guide track in a strapping machine, it follows the track better so that tracking of the strap is better insured, especially when employing lighter gauge strapping. Still another advantage of the corrugations is that it provides a more uniform sealed joint when the overlapping strap ends of a loop of strapping surrounding an object are joined together in an interlocking manner with an encircling metal seal. Another advantage is that the corrugations of the strapping permit automatic longitudinal alignment of overlapping strap ends as a worker manually binds a package. This facilitates the worker placing an encircling seal around two overlapping 3,Z35,il7l Patented Feb. 15, 1966 strap ends prior to the formation of a strap joint. Still another advantage of the corrugations is that it facilitates the shearing of it by inherently providing the cuttting advantages in a plain shear with straight cutting edges as when cuttting with a shear having serrated cuttting edges. Another surprising advantage of the corrugated strapping is that it has greater tensile strength after corrugating than before.

These advantages mentioned apply to the high tensile strapping and some also apply to even lower tensile strapping of types in general use. In addition, the corrugated strapping can be used with special advantage for binding bales of material such as cotton. Presently, when baling cotton, the bales of cotton are first compressed by presses in preparation for the encircling of binding straps. Then, loops of binding straps are encircled around a com pressed bale and the two ends of the strap loop are bent back upon themselves after being presented through openings of a bale tie buckle. At this time the compression of the press is released to allow the bale to expand. While expanding, the strap ends slip around the edges of the openings in the buckle and the bending characteristics of the strap presently used extensively are such that slippage stops when from about 500 to 600 pounds of tension remains in the strap and this determines the limit of expansion of the bale. The typical strap used is about .044 inch by one inch of low carbon hot rolled steel with a 3,000 pound tensile or breaking strength. Since the holding strength of the strap on the buckle is determined by its bending strength, there is apparently about 500 to 600 pounds held by the bent strap and this is far less than the 3,000 pound breaking strength of the strap so that the full strength of the band is not employed.

It has been determined by test that strap of much thinner gauge can be corrugated longitudinally to impart a transverse corrugated cross-section to it which provides the same bending characteristics as the thicker planar strap. In this way, corrugated strap of about .020 inch thick and of about the same quality as previously mentioned with a depth of corrugation of about .040 inch can be used to obtain the same results of arriving at about 500 to 600 pounds in the strap after slippage on the buckle and full expansion of the bale is completed. Such a strap has a tensile or breaking strength of about 1,500 pounds so that it is quite apparent that a greater percentage of the actual strength of the strap is being utilized. ;By comparison, it has been determined by test that .020 inch thick strap without the corrugations results in about only to 200 pounds holding ability by the bent strap which clearly illustrates the unobvious advantage of the corrugations. The holding ability provided by the corrugations is greater than what might be ordinarily expected. Also, this emphasizes the advantage of the invention in providing a savings of material and reduction of weight over the situation when flat strapping is used.

Other objects and advantages of the invention should be apparent upon reference to the accompanying drawings, in which FIG. 1 shows a perspective view of a length of strapping embodying the invention;

FIG. 2 shows a length of strapping being fed between two corrugating rolls to provide the strap with the features of the invention;

FIG. 3 shows a transverse cross-sectional enlarged view of the strap in relation to the corrugating rolls which are partially shown;

FIG. 4 shows a side elevation of a portion of a strap tensioning tool as it appears when being used to tension a length of strap;

FIG. 5 shows a sectional view along the line 55 of FIG. 4;

FIG. 6 shows a perspective view of a continuous length of strapping embodying the invention as it appears when wound into a ribbon wound coil; and

FIG. 7 shows a loop of strap embodying the inven tion as it appears encircled about a bale of material.

The invention shown in FIG. 1 consists of strapping 1 provided with a plurality of equally spaced corrugations 2 which extend uniformly for the entire length of the strapping. The manner of imparting the corrugations to the strapping 1 can be performed in different ways, but a relatively simple manner is to pass the strap 1 between two corrugating rolls 3 and 4. Each of the rolls 3 and 4 are provided with protruding annular rings 3a and 4a which are alternately positioned along the oppositely positioned rolls 3 and 4. When the rolls 3 and 4 are brought close enough together, they deform the strap 1 to provide it with a transverse corrugated cross-section, as best viewed in FIG. 3. The depth of the corrugations is accentuated in FIG. 3 for illustrative purposes.

In FIGS. 4 and 5 is shown the manner in which a conventional strap tensioning gripper 5 engages the strap 1 against a strap support 6 when the strap is to be tensioned. The gripper 5 is provided with sharpened teeth which are used to penetrate the strap 1 in order to grip it. With ordinary strap which is flat across its entire width, these sharpened teeth 5a fail to penetrate sul"- ciently into the strapping to obtain a tight enough bite to permit adequate tensioning of the strap 1. By having the corrugations in the strap 1, the normal force of the gripper 5 against the strap 1 is distributed into a plurality of contact regions where the teeth 5a contact the apices of the corrugations of the strap 1 rather than be distributed evenly across the entire width of the band along each sharpened tooth. This division into small contact regions provides greater force concentrations at these small areas of contact which apparently causes the teeth to grasp or bite into the strap to a greater extent. Regardless of the reason, it has been proven by experiment that the gripping action is far improved and less slippage occurs.

In FIG. 6 a ribbon wound coil 7 of the strapping 1 is shown. A ribbon wound coil is one where its convolutions are wrapped one directly over the other, rather than criss-cross or" each other as in a coil which has been wound in an oscillated manner. Such a ribbon wound coil has proven to be quite rigid so that it will support itself without telescoping which is not true when the strapping is of flat cross-section. This permits the strapping 1 to be ribbon wound in this manner without requiring a spool with side-plates to be used, thus cutting down the expense of packaging.

As previously mentioned, the rigidity provided by the corrugations permits the strap to be used more efficiently when it is fed around a strap guide because it does not have a tendency to fall away from the guide track. At the same time, by keeping the depths of the corrugations to a minimum, the rigidity is not so great that the strap cant be bent around corners as required.

The overall appearance of the strapping with corrugations is enhanced because the corrugations conceal finish imperfections.

The other advantages are that the sealed joints made with the corrugated strapping are more uniform and, therefore, consistently of higher efficiency and the strength of the corrugated strapping has been shown to be higher after corrugating than before. The alignment feature of the corrugations also facilitates maintaining overlapping strap portions aligned when manually binding objects to facilitate the performance of the worker. One of the other advantages is that the corrugated band can be cut with greater facility and inherently embodies the advantages obtained with a shear having serrated cutting edges when using a shear with only straight cutting edges.

As shown particularly in FIG. 7, a bale of cotton or other compressible material is provided with three loops of strap 8 encircled about it. The strap ends 9 and 10 of each strap 8 are bent back upon themselves after passing through slots or openings in bale tie buckles 11. The ends 9 and 10 are positioned toward the surface of the bale to aid in keeping them bent. After the two platens 12 and 13 of a bailing press are separated after compressing the bale and after the application of the three straps 8, the strap ends 9 and 10 slip around the portions of the buckles 11 they engage. The resistance to bending of the strap ends determines the holding ability of the strap ends on the buckles and, in turn, determines how much the bale expands. By using strap of about .020 inch thick and of low carbon hot rolled steel with a width of about one inch, the bending resistance of the ends of the straps will be about 500 to 600 pounds. This is the same holding ability as obtained from the same quality steel which is not corrugated, but which has a thickness of about .044 inch. This means that with approximately one-half the steel, there is equivalent holding ability. As previously mentioned, the holding ability of .020 inch strap without the corrugations is only about to 200 pounds. This indicates that the corrugations produce a bending resistance proportionately greater than what might be expected.

Although only a single embodiment of the invention has been shown and described, it should be clearly understood that the invention can be made in other ways without departing from the true scope of the invention as efined by the appended claims.

We claim:

1. A strap for package binding comprising an elongated ribbon of steel strap having a tensile strength of between approximately 130,000 and 200,000 p.s.i., said strap having a width substantially greater than its thickness and provided with a corrugated transverse cross-sectional shape from edge to edge, said shape being provided by a plurality of longitudinally extending longitudinal corrugations.

2. A bound com-pressed bale comprising a binder strap encircled about the compressed bale with the ends of the strap folded about portions of a bale tic buckle and back upon themselves joining the strap ends into a closed loop about the bale, said strap being of a width substantially greater than its thickness and provided with a corrugated transverse cross-sectional shape to increase the resistance to unfolding of the strap ends around said portions of the bale tie buckle beyond the resistance obtained when non-corrugated strap is used, said shape being provided by a plurality of longitudinally extending substantially equally sized and shaped and substantially equally laterally spaced corrugations formed in the strap.

3. A strap for package binding comprising, an elongated ribbon of strap with a width substantially greater thanits thickness provided with a corrugated transverse cross-sectional shape including longitudinally extending parallel corrugations of uniformly shaped, spaced and sized alternate ridges and furrows on both faces of the strap, said ridges on one face of the strap being directly opposite the furrows on the opposite face of the strap, all of said furrows being of substantially the same depth and size and all of said ridges being of substantially the same height and size.

4. A strap for package binding comprising, an elongated ribbon of strap with a width substantially greater than its thickness provided with a corrugated transverse crosssectional shape including longitudinally extending parallel corrugations of uniformly shaped, spaced and sized alternate ridges and furrows on both faces of the strap, said ridges on one face of the strap being directly opposite the furrows on the opposite face of the strap, all of said furrows being of substantially the same depth and size and all of said ridges being of substantially the same height and size, said strap being composed of steel having a tensile strength of between 130,000 and 200,000

References Cited by the Examiner p. s.i.

UNITED STATES PATENTS 5 Cary 21767 Chaplin 217-92 Meade 217--91 Goldie 217-91 MacMun-ay 21767 10 6 Kimball 217-67 WEiohsel 20660 McKee 20660 Paxton 21767 Simpson 206-60 Ippolito 21791 THERON E. CONDON, Primary Examiner.

LOUIS G. MANCENE, Examiner. 

4. A STRAP FOR PACKAGE BINDING COMPRISING, AN ELONGATED RIBBON OF STRAP WITH A WIDTH SUBSTANTIALLY GREATER THAN ITS THICKNESS PROVIDED WITH A CORRUGATED TRANSVERSE CROSSSECTIONAL SHAPE INCLUDING LONGITUDINALLY EXTENDING PARALLEL CORRUGATIONS OF UNIFORMLY SHAPED, SPACED AND SIZED ALTERNATE RIDGES AND FURROWS ON BOTH FACES OF THE STRAP, SAID RIDGES ON ONE FACE OF THE STRAP BEING DIRECTLY OPPOSITE THE FURROWS ON THE OPPOSITE FACE OF THE STRAP, ALL OF SAID FURROWS BEING OF SUBSTANTIALLY THE SAME DEPTH AND SIZE AND ALL OF SAID RIDGES BEING OF SUBSTANTIALLY THE SAME HEIGHT AND SIZE, SAID STRAP BEING COMPOSED OF STEEL HAVING A TENSILE STRENGTH OF BETWEEN 130,000 AND 200,000 P.S.I. 